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Abstract

Bubble formation due to supersaturation or superheating plays an important role in many different areas from boiling flows to reactions producing gases, such as in electrolytic processes or fermentation. The predominant mechanism for bubble formation is heterogeneous nucleation and, while it has been studied on the microscale, the effect of bubble nucleation on the large-scale performance of bubble column reactors is still scarcely investigated. This work presents a modelling and simulation study on phase transition in bubble column reactors on the meso-scale using a discrete bubble model (DBM). The Discrete Bubble Model is an Euler- Lagrange model which tracks each bubble individually. The model has been extended to include the formation of bubbles due to the presence of supersaturation. With this model, phase transition from liquid to gas in a supersaturated liquid has been studied for two cases: bubble formation on a solid surface and in a liquid bulk. The second case shows a larger number of bubbles formed, with a bigger size. The concentration front presents differences, as in the first case it shifts from a lower concentration at the bottom to the opposite. To conclude, a starting point for simulations of phase transition due to supersaturation has been given in this work, showing that the choice of the mechanisms of bubble formation highly influence bubble densities, sizes and movements in the considered liquid.